I'll choose "Animation and Modern App Design" as the topic. In this example, we'll create a modern and animated login form using PyQt6 and Qt's animation API. **Application Overview** We'll design a login form with a shimmering animation effect on the username and password fields, and a scroll-up animation effect when the login button is clicked. This will give our application a modern and sleek look. **Prerequisites** * PyQt6 installed * Python 3.7+ * Qt 5.15+ **Source Code** ```python import sys from PyQt6.QtCore import * from PyQt6.QtGui import * from PyQt6.QtWidgets import * from PyQt6.Qtanim import * class LoginForm(QDialog): def __init__(self): super().__init__() self.setWindowTitle("Animated Login Form") self.setFixedSize(300, 150) self.layout = QVBoxLayout() self.setLayout(self.layout) self.username_field = QLineEdit() self.username_field.setPlaceholderText("Username") self.layout.addWidget(self.username_field) self.password_field = QLineEdit() self.password_field.setEchoMode(QLineEdit.EchoMode.Password) self.password_field.setPlaceholderText("Password") self.layout.addWidget(self.password_field) self.login_button = QPushButton("Login") self.login_button.clicked.connect(self.animate_login) self.layout.addWidget(self.login_button) self.shimmer_animation(self.username_field) self.shimmer_animation(self.password_field) def shimmer_animation(self, widget): effect = QGraphicsOpacityEffect() widget.setGraphicsEffect(effect) animation = QPropertyAnimation(effect, b"opacity") animation.setStartValue(1.0) animation.setEndValue(0.5) animation.setDuration(1000) animation.setLoopCount(-1) animation.start() def animate_login(self): animation = QPropertyAnimation(self, b"windowOpacity") animation.setStartValue(1.0) animation.setEndValue(0.0) animation.setDuration(500) animation.finished.connect(self.close) animation.start() self.scroll_up_animation(self.username_field) self.scroll_up_animation(self.password_field) self.scroll_up_animation(self.login_button) def scroll_up_animation(self, widget): effect = QGraphicsScaleEffect() widget.setGraphicsEffect(effect) animation = QPropertyAnimation(effect, b"scale") animation.setStartValue(1.0) animation.setKeyValueAt(0.5, 0.5) animation.setEndValue(1.0) animation.setDuration(500) animation.start() if __name__ == "__main__": app = QApplication(sys.argv) form = LoginForm() form.show() sys.exit(app.exec()) ``` **Explanation** In this example, we first create a `LoginForm` class that inherits from `QDialog`. We define a simple layout with two `QLineEdit` widgets for the username and password fields, and a `QPushButton` for the login button. We then create a shimmering animation effect on the username and password fields by setting a `QGraphicsOpacityEffect` with a `QPropertyAnimation` that changes the opacity between 1.0 and 0.5. When the login button is clicked, we animate the login form by changing its opacity to 0.0 over a duration of 500 milliseconds. We also scroll up the username and password fields, and the login button, by setting a `QGraphicsScaleEffect` with a `QPropertyAnimation` that changes the scale to 0.5 and back to 1.0. **Result** When you run the application, you'll see a login form with shimmering animation effects on the username and password fields. When you click the login button, the form will animate up and close. **Conclusion** In this example, we demonstrated how to use PyQt6 and Qt's animation API to create a modern and animated login form. We used `QGraphicsOpacityEffect` and `QPropertyAnimation` to create shimmering animation effects on the username and password fields, and `QGraphicsScaleEffect` and `QPropertyAnimation` to scroll up the fields and the login button. You can use these techniques to create other types of animations and effects in your PyQt6 applications, such as fade-in and fade-out effects, slide-in and slide-out effects, and more.